Touch screen sensor

ABSTRACT

A touch screen sensor includes a visible light transparent substrate and an electrically conductive micropattern disposed on or in the visible light transparent substrate. The micropattern includes a first region micropattern within a touch sensing area and a second region micropattern. The first region micropattern has a first sheet resistance value in a first direction, is visible light transparent, and has at least 90% open area. The second region micropattern has a second sheet resistance value in the first direction. The first sheet resistance value is different from the second sheet resistance value.

BACKGROUND

Touch screen sensors detect the location of an object (for example afinger or a stylus) applied to the surface of a touch screen display orthe location of an object positioned near the surface of a touch screendisplay. These sensors detect the location of the object along thesurface of the display, for example in the plane of a flat rectangulardisplay. Examples of touch screen sensors include capacitive sensors,resistive sensors, and projected capacitive sensors. Such sensorsinclude transparent conductive elements that overlay the display. Theelements are combined with electronic components that use electricalsignals to probe the elements in order to determine the location of anobject near or in contact with the display.

In the field of touch screen sensors, there is a need to have improvedcontrol over the electrical properties of the transparent touch screensensors, without compromising optical quality or properties of thedisplay. A transparent conductive region of a typical touch screensensor includes a continuous coating of a transparent conducting oxide(TCO) such as indium tin oxide (ITO), the coating exhibiting electricalpotential gradients based on the location or locations of contact to avoltage source and the overall shape of the region. This fact leads to aconstraint on possible touch sensor designs and sensor performance, andnecessitates such measures as expensive signal processing electronics orplacement of additional electrodes to modify the electrical potentialgradients. Thus, there is a need for transparent conductive elementsthat offer control over electrical potential gradients that isindependent of the aforementioned factors.

There is an additional need in the field of touch screen sensors thatrelates to flexibility in the design of electrically conductiveelements. The fabrication of touch screen sensors using patternedtransparent conducting oxides (TCO) such as indium tin oxide (ITO) oftenplaces limitations on conductor design. The limitations relate to aconstraint caused by patterning all of the conductive elements from atransparent sheet conductor that has a single value of isotropic sheetresistance.

BRIEF SUMMARY

The present disclosure relates to touch screen sensors having varyingsheet resistance. In a first embodiment, a touch screen sensor includesa visible light transparent substrate and an electrically conductivemicropattern disposed on or in the visible light transparent substrate.The micropattern includes a first region micropattern within a touchsensing area and a second region micropattern. The first regionmicropattern has a first sheet resistance value in a first direction, isvisible light transparent, and has at least 90% open area. The secondregion micropattern has a second sheet resistance value in the firstdirection. The first sheet resistance value is different from the secondsheet resistance value.

In another embodiment, a touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea, the first region micropattern having an anisotropic first sheetresistance, being visible light transparent, and having at least 90%open area.

In another embodiment, a touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea and a second region micropattern. The electrically conductivemicropattern has metallic linear electrically conductive features with athickness of less than 500 nanometers and a width between 0.5 and 5micrometers. The first region micropattern has a first sheet resistancevalue in a first direction between 5 and 500 ohm per square, is visiblelight transparent, and has between 95% and 99.5% open area. The secondregion micropattern has a second sheet resistance value in the firstdirection. The first sheet resistance value is different from the secondsheet resistance value.

In a further embodiment, a touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea. The electrically conductive micropattern includes metallic linearelectrically conductive features having a thickness of less than 500nanometers and a width between 0.5 and 5 micrometers. The first regionmicropattern has an anisotropic first sheet resistance with a differencein sheet resistance values for orthogonal directions of a factor of atleast 1.5, is visible light transparent, and has between 95% and 99.5%open area.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more completely understood in consideration of thefollowing detailed description of various embodiments of the inventionin connection with the accompanying drawings, in which:

FIG. 1 illustrates a schematic diagram of a touch screen sensor 100;

FIG. 2 illustrates a perspective view of a conductive visible lighttransparent region lying within a touch screen sensing area;

FIG. 3 illustrates the conductor micropattern for one embodiment of thetouch screen sensor;

FIG. 4 illustrates a portion of the conductor micropattern illustratedin FIG. 3, the portion including a conductive mesh with selective breaksfor modulating the local sheet resistance as well as a larger feature inthe form of a contact pad;

FIG. 5 is a circuit diagram that approximates the properties of theconductor micropattern illustrated in FIG. 3, where capacitive platesare separated by resistive elements;

FIG. 6 illustrates a modulation in resistance along the horizontal meshbars given in FIG. 3, created by selective breaks in the contiguousmesh;

FIG. 7 illustrates the conductor micropattern for one embodiment of thetouch screen sensor, the micropattern including regions labeled 7 a-7 ewith different sheet resistance created in part by selective breaks inthe electrically conductive micropattern mesh;

FIGS. 7a-7e each illustrate a portion of the varying conductormicropattern illustrated in FIG. 7;

FIG. 8 illustrates the distribution of resistance per unit length alongthe long axis of the wedge-shaped transparent conductive region havingregions 7 a and 7 b therein, as compared with the resistance per unitlength for a similarly shaped region comprising only a uniformtransparent conducting oxide, ITO;

FIG. 9 illustrates the arrangement of layers that are laminated togetherto form one embodiment of the touch screen sensor, an X-Y grid typeprojected capacitive touch screen sensor;

FIG. 10 illustrates the conductor micropattern for the X-layer or theY-layer of an embodiment of the touch screen sensor according to FIG. 9;

FIG. 11 illustrates a portion of the conductor micropattern illustratedin FIG. 10, the portion including a visible light transparent conductivemesh contacting a larger feature in the form of a contact pad, as wellas electrically isolated conductor deposits in the space between themesh regions;

FIG. 12 illustrates the conductor micropattern for the X-layer or theY-layer of another embodiment of the touch screen sensor according toFIG. 9;

FIG. 13 illustrates a portion of the conductor micropattern given inFIG. 12, the portion including a visible light transparent conductivemesh contacting a larger feature in the form of a contact pad, as wellas electrically isolated conductor deposits in the space between themesh regions;

FIG. 14 illustrates the conductor micropattern for the X-layer or theY-layer of another embodiment of the touch screen sensor according toFIG. 9; and

FIG. 15 illustrates a portion of the conductor micropattern given inFIG. 14, the portion including a visible light transparent conductivemesh contacting a larger feature in the form of a contact pad, as wellas electrically isolated conductor deposits in the space between themesh regions.

FIGS. 16, 16 a, and 16 b illustrate various portions of a firstpatterned substrate;

FIGS. 17, 17 a, and 17 b illustrate various portions of a secondpatterned substrate;

FIG. 18 illustrates a projected capacitive touch screen transparentsensor element constructed from the first and second patternedsubstrates of FIGS. 16 and 17.

The figures are not necessarily to scale. Like numbers used in thefigures refer to like components. However, it will be understood thatthe use of a number to refer to a component in a given figure is notintended to limit the component in another figure labeled with the samenumber.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanying setof drawings that form a part hereof and in which are shown by way ofillustration several specific embodiments. It is to be understood thatother embodiments are contemplated and may be made without departingfrom the scope or spirit of the present invention. The followingdetailed description, therefore, is not to be taken in a limiting sense.

All scientific and technical terms used herein have meanings commonlyused in the art unless otherwise specified. The definitions providedherein are to facilitate understanding of certain terms used frequentlyherein and are not meant to limit the scope of the present disclosure.

Unless otherwise indicated, all numbers expressing feature sizes,amounts, and physical properties used in the specification and claimsare to be understood as being modified in all instances by the term“about.” Accordingly, unless indicated to the contrary, the numericalparameters set forth in the foregoing specification and attached claimsare approximations that can vary depending upon the desired propertiessought to be obtained by those skilled in the art utilizing theteachings disclosed herein.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4,and 5) and any range within that range.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” encompass embodiments having pluralreferents, unless the context clearly dictates otherwise. As used inthis specification and the appended claims, the term “or” is generallyemployed in its sense including “and/or” unless the context clearlydictates otherwise.

As used herein, “visible light transparent” refers to the level oftransmission being at least 60 percent transmissive to at least onepolarization state of visible light, where the percent transmission isnormalized to the intensity of the incident, optionally polarized light.It is within the meaning of visible light transparent for an articlethat transmits at least 60 percent of incident light to includemicroscopic features (e.g., dots, squares, or lines with minimumdimension, for example width, between 0.5 and 10 micrometers, or between1 and 5 micrometers) that block light locally to less than 80 percenttransmission (e.g., 0 percent); however, in such cases, for anapproximately equiaxed area including the microscopic feature andmeasuring 1000 times the minimum dimension of the microscopic feature inwidth, the average transmittance is greater than 60 percent.

The present disclosure relates to touch screen sensors with electricaland optical properties that are engineered through design of conductormicropatterns comprised therein. There are several advantages that arecreated for touch screen sensors by the incorporation of the conductormicropatterns described herein.

In some embodiments, the transparent conductive properties within atransparent conductive region are engineered to control the electricalpotential gradient within the touch sensing region during use. Thisleads to simplicity of signal processing electronics and, for some touchscreen sensor types simplicity in the design of (or elimination of theneed for) additional conductor patterns that would otherwise be neededfor electrical potential gradient (electrical field) linearization.

In some embodiments, the electrical properties of the touch screensensors described herein are designed to generate a controlledelectrical potential gradient along a transparent sensor element. Forexample, the electrical properties are designed to create a linearelectrical potential gradient along a particular direction within atransparent conductive region, the overall shape of which wouldordinarily lead to a non-linear gradient if a standard transparentconductor material was used (e.g., continuous ITO coating).

In some embodiments, the electrical properties are designed to create alevel of non-linearity of electrical potential gradient for atransparent conductive region that is greater than that which would bepresent within a transparent conductive region of the same shape butcomprised of a standard transparent conductor material (e.g., continuousITO coating). In more detail, for a rectangular capacitive touch screencomprising a contiguous transparent sheet conductor in the form of amicropatterned conductor with electrical connections made to the cornersof the sensing area, the linearity of electrical potential gradient (anduniformity of electric field) across the sensing area in the verticaland horizontal directions can be improved by engineering the areadistribution of sheet resistance values and anisotropy in such a way asto distribute the field more uniformly.

In other embodiments, the sensor includes conductor elements comprisedof the same conductor material at the same thickness (i.e., height), butwith different effective sheet resistance by virtue of micropatterning.For example, in some embodiments, the same conductor material at thesame thickness (i.e., height) is used to generate conductive traces thatdefine a first micropattern geometry, leading to a first level of sheetresistance in a transparent conductive region, and conductive tracesthat define a second micropattern geometry, leading to a second level ofsheet resistance in a second transparent conductive region.

This disclosure also allows for improved efficiency and resourceutilization in the manufacture of transparent display sensors, forexample through the avoidance of rare elements such as indium for someembodiments, for example embodiments based on micropatterned metalconductors.

The disclosure further relates to contact or proximity sensors for touchinput of information or instructions into electronic devices (e.g.,computers, cellular telephones, etc.). These sensors are visible lighttransparent and useful in direct combination with a display, overlayinga display element, and interfaced with a device that drives the display(as a “touch screen” sensor). The sensor element has a sheet like formand includes at least one electrically insulating visible lighttransparent substrate layer that supports one or more of the following:i) conductive material (e.g., metal) that is mesh patterned onto twodifferent regions of the substrate surface with two different meshdesigns so as to generate two regions with different effective sheetresistance values, where at least one of the regions is a transparentconductive region that lies within the touch-sensing area of the sensor;ii) conductive material (e.g., metal) that is patterned onto the surfaceof the substrate in a mesh geometry so as to generate a transparentconductive region that lies within the touch sensing area of the sensorand that exhibits anisotropic effective sheet resistance; and/or iii)conductive material (e.g., metal) that is patterned onto the surface ofthe substrate in a mesh geometry within an effectively electricallycontinuous transparent conductive region, the geometry varying withinthe region so as to generate different values of local effective sheetresistance in at least one direction (e.g., continuously varying sheetresistance for the transparent conductive region), where the region lieswithin the sensing area of the touch sensor.

The sensing area of a touch sensor is that region of the sensor that isintended to overlay, or that overlays, a viewable portion of aninformation display and is visible light transparent in order to allowviewability of the information display. Viewable portion of theinformation display refers to that portion of an information displaythat has changeable information content, for example the portion of adisplay “screen” that is occupied by pixels, for example the pixels of aliquid crystal display.

This disclosure further relates to touch screen sensors that are of theresistive, capacitive, and projected capacitive types. The visible lighttransparent conductor micropatterns are particularly useful forprojected capacitive touch screen sensors that are integrated withelectronic displays. As a component of projected capacitive touch screensensors, the visible light transparent conductive micropattern areuseful for enabling high touch sensitivity, multi-touch detection, andstylus input.

The two or more different levels of sheet resistance, the anisotropy ofthe sheet resistance, or the varying level of sheet resistance within atransparent conductive region can be controlled by the geometries oftwo-dimensional meshes that make up the transparent micropatternedconductors, as described below.

While the present invention is not so limited, an appreciation ofvarious aspects of the invention will be gained through a discussion ofthe examples provided below.

FIG. 1 illustrates a schematic diagram of a touch screen sensor 100. Thetouch screen sensor 100 includes a touch screen panel 110 having a touchsensing area 105. The touch sensing area 105 is electrically coupled toa touch sensor drive device 120. The touch screen panel 110 isincorporated into a display device.

FIG. 2 illustrates a perspective view of a conductive visible lighttransparent region 101 that would lie within a touch sensing area of atouch screen panel, e.g., touch sensing area 105 in FIG. 1. Theconductive visible light transparent region 101 includes a visible lighttransparent substrate 130 and an electrically conductive micropattern140 disposed on or in the visible light transparent substrate 130. Thevisible light transparent substrate 130 includes a major surface 132 andis electrically insulating. The visible light transparent substrate 130can be formed of any useful electrically insulating material such as,for example, glass or polymer. Examples of useful polymers for lighttransparent substrate 130 include polyethylene terephthalate (PET) andpolyethylene naphthalate (PEN). The electrically conductive micropattern140 can be formed of a plurality of linear metallic features.

FIG. 2 also illustrates an axis system for use in describing theconductive visible light transparent region 101 that would lie within atouch sensing area of a touch screen panel. Generally, for displaydevices, the x and y axes correspond to the width and length of thedisplay and the z axis is typically along the thickness (i.e., height)direction of a display. This convention will be used throughout, unlessotherwise stated. In the axis system of FIG. 2, the x axis and y axisare defined to be parallel to a major surface 132 of the visible lighttransparent substrate 130 and may correspond to width and lengthdirections of a square or rectangular surface. The z axis isperpendicular to that major surface and is typically along the thicknessdirection of the visible light transparent substrate 130. A width of theplurality of linear metallic features that form the electricallyconductive micropattern 140 correspond to an x-direction distance forthe parallel linear metallic features that extend linearly along the yaxis and a y-direction distance for the orthogonal linear metallicfeatures correspond to a width of the orthogonal linear metallicfeatures. A thickness or height of the linear metallic featurescorresponds to a z-direction distance.

In some embodiments, the conductive visible light transparent region 101that would lie within a touch sensing area of a touch screen panelincludes two or more layers of visible light transparent substrate 130each having a conductive micropattern 140.

The conductive micropattern 140 is deposited on the major surface 132.Because the sensor is to be interfaced with a display to form a touchscreen display, or touch panel display, the substrate 130 is visiblelight transparent and substantially planar. The substrate and the sensormay be substantially planar and flexible. By visible light transparent,what is meant is that information (for example, text, images, orfigures) that is rendered by the display can be viewed through the touchsensor. The viewability and transparency can be achieved for touchsensors including conductors in the form of a deposited metal, evenmetal that is deposited with thickness great enough to block light, ifthe metal is deposited in an appropriate micropattern.

The conductive micropattern 140 includes at least one visible lighttransparent conductive region overlaying a viewable portion of thedisplay that renders information. By visible light transparentconductive, what is meant is that the portion of the display can beviewed through the region of conductive micropattern and that the regionof micropattern is electrically conductive in the plane of the pattern,or stated differently, along the major surface of the substrate ontowhich the conductive micropattern is deposited and to which it isadjacent. Preferred conductive micropatterns include regions with twodimensional meshes, for example square grids, rectangular (non-square)grids, or regular hexagonal networks, where conductive traces defineenclosed open areas within the mesh that are not deposited withconductor that is in electrical contact with the traces of the mesh. Theopen spaces and associated conductor traces at their edges are referredto herein as cells. Other useful geometries for mesh cells includerandom cell shapes and irregular polygons.

In some embodiments, the conductive traces defining the conductivemicropattern are designed not to include segments that are approximatelystraight for a distance greater than the combined edge length of fiveadjacent cells, preferably four adjacent cells, more preferably threeadjacent cells, even more preferably two adjacent cells. Mostpreferably, the traces defining the micropattern are designed not toinclude segments that are straight for a distance greater than the edgelength of a single cell. Accordingly, in some embodiments, the tracesthat define the micropattern are not straight over long distances, forexample, 10 centimeters, 1 centimeter, or even 1 mm. Patterns withminimal lengths of straight line segments, as just described, areparticularly useful for touch screen sensors with the advantage ofcausing minimal disturbance of display viewability.

The two-dimensional geometry of the conductive micropattern (that is,geometry of the pattern in the plane or along the major surface of thesubstrate) can be designed, with consideration of the optical andelectrical properties of the conductor material, to achieve specialtransparent conductive properties that are useful in touch screensensors. For example, whereas a continuous (un-patterned) deposit orcoating of conductor material has a sheet resistance that is calculatedas its bulk resistivity divided by its thickness, in the presentinvention different levels of sheet resistance is engineered bymicropatterning the conductor as well.

In some embodiments, the two-dimensional conductive micropattern isdesigned to achieve anisotropic sheet resistance in a conductive region(for example, a visible light transparent conductive region) of thesensor. By anisotropic sheet resistance, what is meant is that themagnitude of the sheet resistance of the conductive micropattern isdifferent when measured or modeled along two orthogonal directions.

In contrast, in some embodiments, the two-dimensional conductivemicropattern is designed to achieve isotropic sheet resistance in aconductive region (for example, a visible light transparent conductiveregion) of the sensor. By isotropic sheet resistance, what is meant isthat the magnitude of the sheet resistance of the conductivemicropattern is the same when measured or modeled along any twoorthogonal directions in the plane, as in the case for a square gridhaving formed with traces of constant width for both directions.

Anisotropic sheet resistance within a region can include sheetresistance in one direction that is at least 10 percent greater than thesheet resistance in the orthogonal direction, or at least 25 percentgreater, at least 50 percent greater, at least 100 percent greater, atleast 200 percent greater, at least 500 percent greater, or even atleast 10 times greater. In some embodiments, anisotropic sheetresistance within a region includes sheet resistance in one directionthat is greater than the sheet resistance in the orthogonal direction bya factor of at least 1.5. In some embodiments, anisotropic sheetresistance within a region includes sheet resistance in one directionthat is greater than the sheet resistance in the orthogonal direction bya factor between 1.1 and 10, in other embodiments between 1.25 and 5,and in yet other embodiments between 1.5 and 2.

An example of a conductive micropattern geometry that can generateanisotropic sheet resistance is approximately a rectangular microgrid(non-square) with fixed widths for the conductive traces. For such arectangular microgrid (non-square), anisotropic sheet resistance canresult from a repeating geometry for the cells of the grid that includesone edge that is 10 percent longer than the other, 25 percent longerthan the other, at least 50 percent longer than the other, 100 percentlonger than the other, or even 10 times longer than the other.Anisotropic sheet resistance can be created by varying the width oftraces for different directions, for example in an otherwise highlysymmetrical pattern of cells for a mesh. An example of the latterapproach to generating anisotropic sheet resistance is a square grid ofconductive traces, for example with pitch of 200 micrometers, whereinthe traces in a first direction are 10 micrometers wide and the tracesin the orthogonal direction are 9 micrometers in width, 7.5 micrometersin width, 5 micrometers in width, or even 1 micrometer in width.Anisotropic sheet resistance within a region can include a finite,measurable sheet resistance in one direction and essentially infinitesheet resistance in the other direction, as would be generated by apattern of parallel conductive lines. In some embodiments, as describedabove, the anisotropic sheet resistance within a region includes afinite, measurable sheet resistance in a first direction and a finite,measurable sheet resistance in the direction orthogonal to the firstdirection.

For the purpose of determining whether a region of conductivemicropattern is isotropic or anisotropic, it will be appreciated bythose skilled in the art that the scale of the region of interest mustbe reasonably selected, relative to the scale of the micropattern, tomake relevant measurements or calculations of properties. For example,once a conductor is patterned at all, it is trivial for one to select alocation and a scale on which to make a measurement that will yield adifference in sheet resistance for different directions of measurement.The following detailed example can make the point more clearly. If oneconsidered a conductor pattern of isotropic geometry in the form of asquare grid with 100 micrometer wide conductor traces and 1 mm pitch(leading to 900 micrometer by 900 micrometer square openings in thegrid), and one made four point probe measurements of sheet resistancewithin one of the traces along the edge of a square opening with a probehaving fixed spacing along the four linearly arranged probes of 25micrometers (leading to a separation between the two current probes, theoutside probes, of 75 micrometers), different levels of sheet resistancewill be calculated by the measured values of current and voltagedepending on whether the probes were aligned parallel to the trace ororthogonal to the trace. Thus, even though the square grid geometrywould yield isotropic sheet resistance on a scale larger than the squaregrid cell size, it is possible for one to carry out measurements ofsheet resistance that would suggest anisotropy. Thus, for the purpose ofdefining anisotropy of the sheet resistance of a conductive micropatternin the current disclosure, for example a visible light transparentconductive region of the micropattern that comprises a mesh, therelevant scale over which the sheet resistance should be measured ormodeled is greater than the length scale of a cell in the mesh,preferably greater than the length scale of two cells. In some cases,the sheet resistance is measured or modeled over the length scale offive or more cells in the mesh, to show that the mesh is anisotropic inits sheet resistance.

In contrast to embodiments where the conductive micropattern exhibitsanisotropy of sheet resistance in a region, sensors includingtransparent conducting oxide thin films (for example, indium tin oxide,or ITO) exhibit isotropic sheet resistance in contiguous regions of theconductor. In the latter case, one can measure or model that asfour-point probe measurements of sheet resistance of a contiguous regionare made in different directions and with decreasing spacing between theprobes, the same readings of current and voltage for differentdirections clearly indicate isotropy.

In some embodiments, the two-dimensional conductive micropattern isdesigned to achieve different levels, or magnitudes, of sheet resistancein two different patterned conductor regions of the sensor, whenmeasured in a given direction. For example, with respect to thedifferent levels of sheet resistance, the greater of the two may exceedthe lesser by a factor greater than 1.25, a factor greater than 1.5, afactor greater than 2, a factor greater than 5, a factor greater than10, or even a factor greater than 100. In some embodiments, the greaterof the two sheet resistance values exceeds the lesser by a factorbetween 1.25 and 1000, in other embodiments between 1.25 and 100, inother embodiments between 1.25 and 10, in other embodiments between 2and 5. For a region to be regarded as having a different sheetresistance from that of another region, it would have a sheet resistancethat is greater or lesser than that of the other region by a factor ofat least 1.1.

In some embodiments, the micropattern is designed to achieve theaforementioned different levels of sheet resistance for two patternedconductor regions that are electrically contiguous, which is to say thatthey are patterned conductor regions that are in electrical contact witheach other along a boundary between them. Each of the two patternedconductor regions that share a conductive boundary may have uniformrespective pattern geometries, but again different. In some embodiments,the micropattern is designed to achieve the different levels of sheetresistance for two different patterned conductor regions that areelectrically noncontiguous, which is to say that the they are patternedconductor regions that share no boundary between them for which thepatterned regions are in electrical contact along that boundary. Each ofthe two patterned conductor regions that share no conductive boundarybetween them may have uniform respective pattern geometries, but againdifferent. For electrically noncontiguous regions, it is within thescope of the disclosure for them both to make electrical contact in thepattern to the same solid conductor element, for example a bus bar orpad. In some embodiments, the micropattern is designed to achieve thedifferent levels of sheet resistance for two regions that areelectrically isolated from each other and thus can be addressedindependently by electrical signals. Each of the two mesh regions thatare electrically isolated may have a uniform pattern geometry, but againdifferent. Finally, in some embodiments, the micropattern is designed toachieve different levels of sheet resistance for two different regionsby creating continuously varying sheet resistance from the first regionto the second, and example of two regions that are electricallycontiguous.

The two dimensional conductive micropatterns that include two regionswith different sheet resistance in a measurement direction are usefulfor designing a visible light transparent conductive region in thesensing area with a preferred level of sheet resistance for that region(for example, low sheet resistance between 5 and 100 ohms per square),including varying or anisotropic sheet resistance optionally, anddesigning an electrical element, for example a resistor element, as partof the touch screen sensor that may or may not lie within the sensingarea, the resistor element comprising a sheet conductor with sheetresistance selected optimally for the resistor function (for example,higher sheet resistance between 150 and 1000 ohms per square) andpossibly in light of other design constraints, for example theconstraint of minimizing the footprint of the resistor.

The sheet resistance of the conductive micropattern, in regions anddirections with finite sheet resistance that can be measured or modeled,as described above, may fall within the range of 0.01 ohms per square to1 megaohm per square, or within the range of 0.1 to 1000 ohms persquare, or within the range of 1 to 500 ohms per square. In someembodiments, the sheet resistance of the conductive micropattern fallswithin the range of 1 to 50 ohms per square. In other embodiments, thesheet resistance of the conductive micropattern falls within the rangeof 5 to 500 ohms per square. In other embodiments, the sheet resistanceof the conductive micropattern falls within the range of 5 to 100 ohmsper square. In other embodiments, the sheet resistance of the conductivemicropattern falls within the range of 5 to 40 ohms per square. In otherembodiments, the sheet resistance of the conductive micropattern fallswithin the range of 10 to 30 ohms per square. In prescribing the sheetresistance that may characterize a conductive micropattern or a regionof a conductive micropattern, the micropattern or region of micropatternis said to have a sheet resistance of a given value if it has that sheetresistance value for electrical conduction in any direction.

Appropriate micropatterns of conductor for achieving transparency of thesensor and viewability of a display through the sensor have certainattributes. First of all, regions of the conductive micropattern throughwhich the display is to be viewed should have area fraction of thesensor that is shadowed by the conductor of less than 50%, or less than25%, or less than 20%, or less than 10%, or less than 5%, or less than4%, or less than 3%, or less than 2%, or less than 1%, or in a rangefrom 0.25 to 0.75%, or less than 0.5%.

The open area fraction (or open area) of a conductive micropattern, orregion of a conductive micropattern, is the proportion of themicropattern area or region area that is not shadowed by the conductor.The open area is equal to one minus the area fraction that is shadowedby the conductor, and may be expressed conveniently, andinterchangeably, as a decimal or a percentage. Thus, for the valuesgiven in the above paragraph for the fraction shadowed by conductor, theopen area values are greater than 50%, greater than 75%, greater than80%, greater than 90%, greater than 95%, greater than 96%, greater than97%, greater than 98%, greater than 99%, 99.25 to 99.75%, and greaterthan 99.5%. In some embodiments, the open area of a region of theconductor micropattern (for example, a visible light transparentconductive region) is between 80% and 99.5%, in other embodimentsbetween 90% and 99.5%, in other embodiments between 95% and 99%, inother embodiments between 96% and 99.5%, and in other embodimentsbetween 97% and 98%. With respect to the reproducible achievement ofuseful optical properties (for example high transmission andinvisibility of conductive pattern elements) and electrical properties,using practical manufacturing methods, preferred values of open area arebetween 90 and 99.5%, more preferably between 95 and 99.5%, mostpreferably between 95 and 99%.

To minimize interference with the pixel pattern of the display and toavoid viewability of the pattern elements (for example, conductor lines)by the naked eye of a user or viewer, the minimum dimension of theconductive pattern elements (for example, the width of a line orconductive trace) should be less than or equal to approximately 50micrometers, or less than or equal to approximately 25 micrometers, orless than or equal to approximately 10 micrometers, or less than orequal to approximately 5 micrometers, or less than or equal toapproximately 4 micrometers, or less than or equal to approximately 3micrometers, or less than or equal to approximately 2 micrometers, orless than or equal to approximately 1 micrometer, or less than or equalto approximately 0.5 micrometer.

In some embodiments, the minimum dimension of conductive patternelements is between 0.5 and 50 micrometers, in other embodiments between0.5 and 25 micrometers, in other embodiments between 1 and 10micrometers, in other embodiments between 1 and 5 micrometers, in otherembodiments between 1 and 4 micrometers, in other embodiments between 1and 3 micrometers, in other embodiments between 0.5 and 3 micrometers,and in other embodiments between 0.5 and 2 micrometers. With respect tothe reproducible achievement of useful optical properties (for examplehigh transmission and invisibility of conductive pattern elements withthe naked eye) and electrical properties, and in light of the constraintof using practical manufacturing methods, preferred values of minimumdimension of conductive pattern elements are between 0.5 and 5micrometers, more preferably between 1 and 4 micrometers, and mostpreferably between 1 and 3 micrometers.

In general, the deposited electrically conductive material reduces thelight transmission of the touch sensor, undesirably. Basically, whereverthere is electrically conductive material deposited, the display isshadowed in terms of its viewability by a user. The degree ofattenuation caused by the conductor material is proportional to the areafraction of the sensor or region of the sensor that is covered byconductor, within the conductor micropattern.

In some embodiments, in order to generate a visible light transparentdisplay sensor that has uniform light transmission across the viewabledisplay field, even if there is a non-uniform distribution of sheetresistance, for example derived from a non-uniform mesh of conductivematerial, the sensors include isolated conductor deposits added to theconductor micropattern that serve to maintain the uniformity of lighttransmittance across the pattern. Such isolated conductor deposits arenot connected to the drive device (for example, electrical circuit orcomputer) for the sensor and thus do not serve an electrical function.For example, a metal conductor micropattern that includes a first regionwith a mesh of square grid geometry of 3 micrometer line width and 200micrometer pitch (3 percent of the area is shadowed by the metal, i.e.,97% open area) and second region with a mesh of square grid geometry of3 micrometer line width and 300 micrometer pitch (2 percent of the areais shadowed by the metal, i.e., 98% open area) can be made opticallyuniform in its average light transmission across the two regions byincluding within each of the open cells of the 300 micrometer pitch gridregion one hundred evenly spaced 3 micrometer by 3 micrometer squares ofmetal conductor in the pattern. The one hundred 3 micrometer by 3micrometer squares (900 square micrometers) shadow an additional 1percent of the area for each 300 micrometer by 300 micrometer cell(90000 square micrometers), this making the average light transmissionof the second region equal to that of the first region. Similar isolatedmetal features can be added in regions of space between contiguoustransparent conductive regions, for example contiguous transparentconductive regions that include micropatterned conductor in the form ofa two dimensional meshes or networks, in order to maintain uniformity oflight transmittance across the sensor, including the transparentconductive regions and the region of space between them. In addition toisolated squares of conductor, other useful isolated deposits ofconductor for tailoring optical uniformity include circles and lines.The minimum dimension of the electrically isolated deposits (e.g., theedge length of a square feature, the diameter of a circular feature, orthe width of a linear feature) is less than 10 micrometers, less than 5micrometers, less than 2 micrometers, or even less than 1 micrometer.

With respect to the reproducible achievement of useful opticalproperties (for example high transmission and invisibility of conductivepattern elements), using practical manufacturing methods, the minimumdimension of the electrically isolated deposits is preferably between0.5 and 10 micrometers, more preferably between 0.5 and 5 micrometers,even more preferably between 0.5 and 4 micrometers, even more preferablybetween 1 and 4 micrometers, and most preferably between 1 and 3micrometers. In some embodiments, the arrangement of electricallyisolated conductor deposits is designed to lack periodicity. A lack ofperiodicity is preferred for limiting unfavorable visible interactionswith the periodic pixel pattern of an underlying display. For anensemble of electrically isolated conductor deposits to lackperiodicity, there need only be a single disruption to the otherwiseperiodic placement of at least a portion of the deposits, across aregion having the deposits and lacking micropattern elements that areconnected to decoding or signal generation and/or processingelectronics. Such electrically isolated conductor deposits are said tohave an aperiodic arrangement, or are said to be an aperiodicarrangement of electrically isolated conductor deposits. In someembodiments, the electrically isolated conductor deposits are designedto lack straight, parallel edges spaced closer than 10 micrometersapart, for example as would exist for opposing faces of a square depositwith edge length of 5 micrometers. More preferably the isolatedconductor deposits are designed to lack straight, parallel edges spacedcloser than 5 micrometers apart, more preferably 4 micrometers apart,even more preferably 3 micrometers apart, even more preferably 2micrometers apart. Examples of electrically isolated conductor depositsthat lack straight, parallel edges are ellipses, circles, pentagons,heptagons, and triangles. The absence within the design of electricallyisolated conductor deposits of straight, parallel edges serves tominimize light-diffractive artifacts that could disrupt the viewabilityof a display that integrates the sensor.

The impact of the conductor micropattern on optical uniformity can bequantified. If the total area of the sensor, and hence the conductormicropattern, that overlays a viewable region of the display issegmented into an array of 1 mm by 1 mm regions, preferred sensorsinclude conductor micropatterns wherein none of the regions have ashadowed area fraction that differs by greater than 75 percent from theaverage for all of the regions. More preferably, none have a shadowedarea fraction that differs by greater than 50 percent. More preferably,none have a shadowed area fraction that differs by greater than 25percent. Even more preferably, none have a shadowed area fraction thatdiffers by greater than 10 percent. If the total area of the sensor, andhence the conductor micropattern, that overlays a viewable region of thedisplay is segmented into an array of 5 mm by 5 mm regions, preferredsensors include conductor micropatterns wherein none of the regions havea shadowed area fraction that differs by greater than 50 percent fromthe average for all of the regions. Preferably, none have a shadowedarea fraction that differs by greater than 50 percent. More preferably,none have a shadowed area fraction that differs by greater than 25percent. Even more preferably, none have a shadowed area fraction thatdiffers by greater than 10 percent.

The disclosure advantageously allows for the use of metals as theconductive material in a transparent conductive sensor, as opposed totransparent conducting oxides (TCO's), such as ITO. ITO has certaindrawbacks, such as corrosion-related degradation in certainconstructions, a tendency to crack when flexed, high attenuation oftransmitted light (due to reflection and absorption) when deposited as acoating with sheet resistance below 100 to 1000 ohms per square, andincreasing cost due to the scarcity of indium. ITO is also difficult todeposit with uniform and reproducible electrical properties, leading tothe need for more complex and expensive electronics that couple to theconductive pattern to construct a touch screen sensor.

Examples of useful metals for forming the electrically conductivemicropattern include gold, silver, palladium, platinum, aluminum,copper, nickel, tin, alloys, and combinations thereof. In someembodiments, the conductor is a transparent conducting oxide. In someembodiments the conductor is ITO. The conductor may have a thicknessbetween 5 nanometers and 5 micrometers, or between 10 nanometers and 500nanometers, or between 15 nanometers and 250 nanometers. In manyembodiments, the thickness of the conductor is less than one micrometer.A desired thickness for the conductor can be calculated by starting withthe desired sheet resistance and considering the micropattern geometry(and in turn its effect on the current-carrying cross-section in theplane) and the bulk resistivity of the conductor, as is known in theart. For complicated geometries of micropattern, there are computationalmethods in the art, for example finite difference methods or finiteelement methods that can be used to calculate sheet resistance, referredto herein as modeling the properties of a micropattern. Sheet resistancecan be measured using a number of techniques, including four-point probetechniques and non-contact eddy-current methods, as are known in theart.

Examples of useful displays with which sensors of the invention can beintegrated include liquid crystal displays, cathode ray tube displays,plasma display panels, organic light emitting diode displays.

Conductor patterns according to the invention can be generated by anyappropriate patterning method, for example methods that includephotolithography with etching or photolithography with plating (see,e.g., U.S. Pat. Nos. 5,126,007; 5,492,611; 6,775,907).

In some embodiments, transparent conductive regions with different sheetresistance in at least one direction are created by including selectivebreaks in conductive traces within an otherwise continuous and uniformmesh. This approach of selective placement of breaks is especiallyuseful for generating articles including patterns of visible transparentconductive regions where the optical transmittance across the article isuniform. The starting mesh can be isotropic or anisotropic. For example,an elongated rectangular transparent conductive bar having a squaremicromesh can be made to exhibit periodic sheet resistance along itslong axis by creating a periodic series of breaks, the breaks being intraces that have a vector component in the direction of the long axisand the periodicity being in the direction of the long axis. Thisperiodicity in sheet resistance can be useful for decoding the positionof an object (e.g., a finger) near the rectangular bar. By selecting thewidth, thickness, and area density of traces, together with thepopulation of breaks, one can design periodic variation in theresistance per unit length along a transparent conductive elementcharacterized by peaks in resistance per unit length that are at least 2times the minimum in resistance per unit length, preferably at least 5times their minimum, more preferably at least 10 times there minimum.

In other embodiments that include selective breaks in an otherwisecontinuous and uniform mesh, the breaks can be placed in order to createapproximately continuously varying sheet resistance in a givendirection. The continuously varying sheet resistance can be useful foramplifying the non-linearity of electric field along a transparentconductive element, beyond that which would be created only by theoverall shape of the element. For example, as is known in the art, atransparent conductive element with uniform sheet resistance, in theform of an elongated isosceles triangle with an electrical potentialapplied to its base relative to its apex, exhibits non-linear electricfield from base to apex due to the gradient in resistance per unitlength along the field direction (created by the narrowing width of thetriangle). For touch sensors based on interdigitated arrays of suchtriangular transparent conductive elements, it would be advantageous forthe non-linearity in electric field to be even greater, leading togreater signal-to-noise ratio for circuitry used to decode the positionof an object (e.g., a finger) near the array. By selecting the width,thickness, and area density of traces, together with the population ofbreaks, one can design sheet resistance per unit length along atransparent conductive element that increases by a factor of at least1.1 over a distance of 1 centimeter, or at least 1.2, or at least 1.5,or at least 2.

In some embodiments, two transparent conductive regions with differentsheet resistance in at least one direction are created by including ineach of the two regions a contiguous mesh with its own design, each meshnot necessarily including selectively placed breaks. Examples of twomeshes with designs that lead to different values of sheet resistancefor current passing in a single direction, for example the x directionin FIG. 2, include two meshes with the same thickness (dimension in thez direction in FIG. 2) of the same conductive material deposit but withdifferent amounts with current-carrying cross-sectional area (y-z planein FIG. 2) per unit width in the y direction. One example of such a pairof mesh regions are two square grid regions each comprising conductivetraces of width 2 micrometers but with different pitch, for example 100micrometers and 200 micrometers. Another example of such a pair of meshregions are two rectangular grid regions (non-square, with 100micrometer pitch in the one direction and 200 micrometer pitch in theorthogonal direction) each comprising conductive traces of width 2micrometers but with different orientation, for example with the longaxes of the rectangular cells in the first regions oriented at 90degrees with respect to the rectangular cells in the second region.

In some embodiments, the sensors include an insulating visible lighttransparent substrate layer that supports a pattern of conductor, thepattern includes a visible light transparent micropattern region and aregion having a larger feature that is not transparent, wherein thevisible light transparent micropattern region and the larger featureregion include a patterned deposit of the same conductor (for example, ametal) at approximately the same thickness. The larger feature can takethe form of, for example, a wide conductive trace that makes contact toa visible light transparent conductive micropattern region or a pad formaking contact with an electronic decoding, signal generation, or signalprocessing device. The width of useful larger features, in combinationon the same insulating layer with visible light transparent conductivemicropattern regions, is for example between 25 micrometers and 3 mms,between 25 micrometers and 1 mm, between 25 micrometers and 500micrometers, between 25 micrometers and 250 micrometers, or between 50micrometers and 100 micrometers.

One illustrative touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea and a second region micropattern. The electrically conductivemicropattern includes metallic linear electrically conductive featureshaving a thickness of less than 500 nanometers and a width between 0.5and 5 micrometers. The first region micropattern has a first sheetresistance value in a first direction between 5 and 500 ohm per square,is visible light transparent, and has between 95% and 99.5% open area.The second region micropattern has a second sheet resistance value inthe first direction that is different than the first sheet resistancevalue.

Another illustrative touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea. The electrically conductive micropattern includes metallic linearelectrically conductive features having a thickness of less than 500nanometers and a width between 0.5 and 5 micrometers. The first regionmicropattern has an anisotropic first sheet resistance with a differencein sheet resistance values for orthogonal directions of a factor of atleast 1.5, is visible light transparent, and has between 95% and 99.5%open area.

Another illustrative touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea and a second region micropattern. The electrically conductivemicropattern includes metallic linear electrically conductive featureshaving a thickness of less than 500 nanometers and a width between 1 and4 micrometers. The first region micropattern has a first sheetresistance value in a first direction between 5 and 100 ohm per square,is visible light transparent, and has between 96% and 99.5% open area.The second region micropattern has a second sheet resistance value inthe first direction that is different than the first sheet resistancevalue.

Another illustrative touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea and a second region micropattern. The electrically conductivemicropattern includes metallic linear electrically conductive featureshaving a thickness of less than 500 nanometers and a width between 0.5and 5 micrometers. The first region micropattern has a first sheetresistance value in a first direction between 5 and 500 ohm per square,is visible light transparent, and has between 95% and 99.5% open area.The second region micropattern has a second sheet resistance value inthe first direction that is different than the first sheet resistancevalue. The micropattern also includes electrically isolated conductordeposits. For all 1 mm by 1 mm square regions of the sensor that lie inthe visible light transparent sensing area, none of the regions have ashadowed area fraction that differs by greater than 75 percent from theaverage for all of the regions.

Another illustrative touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea and a second region micropattern. The electrically conductivemicropattern includes metallic linear electrically conductive featureshaving a thickness of less than 500 nanometers and a width between 0.5and 5 micrometers. The first region micropattern has a first sheetresistance value in a first direction between 5 and 500 ohm per square,is visible light transparent, and has between 95% and 99.5% open area.The second region micropattern has a second sheet resistance value inthe first direction that is different than the first sheet resistancevalue. The micropattern also includes electrically isolated conductordeposits. For all 5 mm by 5 mm square regions of the sensor that lie inthe visible light transparent sensing area, none of the regions have ashadowed area fraction that differs by greater than 50 percent from theaverage for all of the regions.

Another illustrative touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea. The electrically conductive micropattern includes metallic linearelectrically conductive features having a thickness of less than 500nanometers and a width between 1 and 4 micrometers. The first regionmicropattern has an anisotropic first sheet resistance with a differencein sheet resistance values for orthogonal directions of a factor of atleast 1.5, is visible light transparent, and has between 96% and 99.5%open area.

Another illustrative touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea. The electrically conductive micropattern includes metallic linearelectrically conductive features having a thickness of less than 500nanometers and a width between 0.5 and 5 micrometers. The first regionmicropattern has an anisotropic first sheet resistance with a differencein sheet resistance values for orthogonal directions of a factor of atleast 1.5, is visible light transparent, and has between 95% and 99.5%open area. The micropattern also includes electrically isolatedconductor deposits. For all 1 mm by 1 mm square regions of the sensorthat lie in the visible light transparent sensing area, none of theregions have a shadowed area fraction that differs by greater than 75percent from the average for all of the regions.

Another illustrative touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea. The electrically conductive micropattern includes metallic linearelectrically conductive features having a thickness of less than 500nanometers and a width between 0.5 and 5 micrometers. The first regionmicropattern has an anisotropic first sheet resistance with a differencein sheet resistance values for orthogonal directions of a factor of atleast 1.5, is visible light transparent, and has between 95% and 99.5%open area. The micropattern also includes electrically isolatedconductor deposits. For all 5 mm by 5 mm square regions of the sensorthat lie in the visible light transparent sensing area, none of theregions have a shadowed area fraction that differs by greater than 50percent from the average for all of the regions.

Another illustrative touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea. The electrically conductive micropattern includes metallic linearelectrically conductive features having a thickness of less than 500nanometers and a width between 0.5 and 5 micrometers. The first regionmicropattern is visible light transparent, and has between 95% and 99.5%open area. The micropattern also includes electrically isolatedconductor deposits. For all 1 mm by 1 mm square regions of the sensorthat lie in the visible light transparent sensing area, none of theregions have a shadowed area fraction that differs by greater than 75percent from the average for all of the regions.

Another illustrative touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea. The electrically conductive micropattern includes metallic linearelectrically conductive features having a thickness of less than 500nanometers and a width between 0.5 and 5 micrometers. The first regionmicropattern is visible light transparent, and has between 95% and 99.5%open area. The micropattern also includes electrically isolatedconductor deposits. For all 5 mm by 5 mm square regions of the sensorthat lie in the visible light transparent sensing area, none of theregions have a shadowed area fraction that differs by greater than 50percent from the average for all of the regions.

Another illustrative touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea. The electrically conductive micropattern includes metallic linearelectrically conductive features having a thickness of less than 500nanometers and a width between 0.5 and 5 micrometers. The first regionmicropattern has a first sheet resistance value in a first directionbetween 5 and 100 ohm per square, is visible light transparent, and hasbetween 95% and 99.5% open area. The micropattern also includeselectrically isolated conductor deposits. For all 1 mm by 1 mm squareregions of the sensor that lie in the visible light transparent sensingarea, none of the regions have a shadowed area fraction that differs bygreater than 75 percent from the average for all of the regions.

Another illustrative touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea. The electrically conductive micropattern includes metallic linearelectrically conductive features having a thickness of less than 500nanometers and a width between 0.5 and 5 micrometers. The first regionmicropattern has a first sheet resistance value in a first directionbetween 5 and 100 ohm per square, is visible light transparent, and hasbetween 95% and 99.5% open area. The micropattern also includeselectrically isolated conductor deposits. For all 5 mm by 5 mm squareregions of the sensor that lie in the visible light transparent sensingarea, none of the regions have a shadowed area fraction that differs bygreater than 50 percent from the average for all of the regions.

Another illustrative touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea and a second region micropattern. The electrically conductivemicropattern includes metallic linear electrically conductive featureshaving a thickness of less than 500 nanometers and a width between 0.5and 5 micrometers. The first region micropattern has a first sheetresistance value in a first direction between 5 and 500 ohm per square,is visible light transparent, and has between 95% and 99.5% open area.The second region micropattern has a second sheet resistance value inthe first direction that is different than the first sheet resistancevalue. The sensor also includes larger electrically conductive featuresdisposed on or in the visible light transparent substrate, the largerfeatures comprising a continuous conductor deposit of the same materialand thickness as included in the micropattern and measuring at least 25micrometers in minimum dimension.

Another illustrative touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea. The electrically conductive micropattern includes metallic linearelectrically conductive features having a thickness of less than 500nanometers and a width between 0.5 and 5 micrometers. The first regionmicropattern has an anisotropic first sheet resistance with a differencein sheet resistance values for orthogonal directions of a factor of atleast 1.5, is visible light transparent, and has between 95% and 99.5%open area. The sensor also includes larger electrically conductivefeatures disposed on or in the visible light transparent substrate, thelarger features comprising a continuous conductor deposit of the samematerial and thickness as included in the micropattern and measuring atleast 25 micrometers in minimum dimension.

Another illustrative touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea and a second region micropattern. The electrically conductivemicropattern includes metallic linear electrically conductive featureshaving a thickness of less than 500 nanometers and a width between 0.5and 5 micrometers. The first region micropattern has a first sheetresistance value in a first direction between 5 and 500 ohm per square,is visible light transparent, and has between 95% and 99.5% open area.The second region micropattern has a second sheet resistance value inthe first direction that is different than the first sheet resistancevalue. The sensor also includes larger electrically conductive featuresdisposed on or in the visible light transparent substrate, the largerfeatures comprising a continuous conductor deposit of the same materialand thickness as included in the micropattern and measuring at least 500micrometers in minimum dimension.

Another illustrative touch screen sensor includes a visible lighttransparent substrate and an electrically conductive micropatterndisposed on or in the visible light transparent substrate. Themicropattern includes a first region micropattern within a touch sensingarea. The electrically conductive micropattern includes metallic linearelectrically conductive features having a thickness of less than 500nanometers and a width between 0.5 and 5 micrometers. The first regionmicropattern has an anisotropic first sheet resistance with a differencein sheet resistance values for orthogonal directions of a factor of atleast 1.5, is visible light transparent, and has between 95% and 99.5%open area. The sensor also includes larger electrically conductivefeatures disposed on or in the visible light transparent substrate, thelarger features comprising a continuous conductor deposit of the samematerial and thickness as included in the micropattern and measuring atleast 500 micrometers in minimum dimension.

EXAMPLES

The following describe exemplary touch screen sensor designs. They canbe fabricated using known photolithographic methods, for example asdescribed in U.S. Pat. No. 5,126,007 or 5,492,611. The conductor can bedeposited using physical vapor deposition methods, for examplesputtering or evaporation, as is known in the art. Each conductivepattern exemplified herein is useful as a transparent touch screensensor, when connected to decoding circuitry, as is known in the art(e.g., U.S. Pat. Nos. 4,087,625; 5,386,219; 6,297,811; WO 2005/121940A2).

Example 1

A micropattern of thin film gold according to the following descriptionis deposited onto a thin sheet of colorless glass (approximately 1 mm inthickness). The micropattern 240 is depicted in FIG. 3 and FIG. 4. Thethickness or height of the gold layer is about 100 nanometers. Themicropattern 240 involves a series of horizontal (x-axis) mesh bars 241comprising horizontal narrow traces 242, the traces 242 measuringapproximately 2 micrometers in width. Four of these horizontal meshtraces 242 are in electrical communication with a larger feature contactpad 260. The mesh bars measure approximately 6 mm in width. Accordingly,with thirteen evenly spaced traces 244 traversing a width (y-axis) of 6mm and thirteen evenly spaced traces 242 traversing a length (x-axis) of6 mm, the pitch of the square grid of traces is 500 micrometers. Asdepicted in FIG. 4, certain traces have breaks 250, measuringapproximately 25 micrometers (exaggerated in the figures, for ease inlocating). For a square grid with 2 micrometers wide opaque traces on a500 micrometer pitch, the fill factor for opaque traces is 0.80%, thusleading to an open area of 99.20%. For the same square grid, except witha 25 micrometer break every 500 micrometers, the fill factor is 0.78%,thus leading to an open area of 99.22%. Thus, the design includes 1 mm×6mm regions with 99.22% open area and 6 mm×6 mm regions with 99.20% openarea. The average visible transmittance of the glass article with meshis approximately 0.92×0.992=91% (with the factor of 0.92 related tointerfacial reflection losses in light transmission in thenon-conductor-deposited areas of the pattern). Along the horizontal bardirection, there is a series of complete grid regions connected togetherby four traces of gold. Assuming an effective bulk resistivity of 5E-06ohm-cm for sputtered thin film gold, each 2 micrometer wide, 500micrometer long segment of thin film gold has a resistance ofapproximately 125 ohms. The regions with a completed grid, for currentpassing in the direction of the bars, have an effective sheet resistanceof approximately 115 ohms per square. The four traces connecting theregions with completed grids create approximately 62.5 ohms ofresistance between the regions. The above described arrangement ofconductive trace elements leads to a spatially varying resistance perunit length along the bar direction as plotted in FIG. 6. FIG. 5illustrates an equivalent circuit for the array of horizontal mesh bars.The circuit has a series of plates connected by resistors.

Example 2

A micropattern of thin film gold according to the following descriptionis deposited onto a thin sheet of colorless glass (approximately 1 mm inthickness). The micropattern 340 is depicted in FIG. 7. The thickness ofthe gold is about 100 nanometers. The micropattern 340 has transparentconductive regions in the form of a series of interdigitated wedges ortriangles. Each wedge is comprised of a mesh made up of narrow metallictraces 342, 344, the traces 342, 344 (see FIG. 7a -FIG. 7c ) measuringapproximately 2 micrometers in width. The mesh wedges measureapproximately 1 centimeter in width at their base and approximately sixcentimeters in length. The pitch of the square grid of traces 342, 344is 500 micrometers. Within selected regions of the mesh (see FIG. 7a-FIG. 7b ), within a wedge, breaks 350 measuring approximately 25micrometers in length are placed intentionally to affect the local sheetresistance within the wedge, for current passing along its long axis. Asdepicted in FIG. 7a and FIG. 7b , regions 7 a and 7 b (the regions beingseparated by approximately 1 centimeter in FIG. 7), breaks 350 areincluded in the mesh that increase the sheet resistance in the directionof the long axis by a factor greater than 1.2. The overall design alsoincludes region 7 c (as depicted in FIG. 7c ), which is electricallyisolated and spaced apart from regions 7 a and 7 b, and which has a meshof with sheet resistance value less than those of regions 7 a and 7 b.The mesh region 7 c has an open area of 99.20%, while the mesh regions 7a and 7 b have open area fractions of 99.20% and 99.21% respectively.The overall design also includes regions 7 d and 7 e (as depicted inFIG. 7d and FIG. 7e ) with meshes of larger pitch than regions 7 a, 7 band 7 c, but with the same width of traces, leading to increased sheetresistance and visible transmittance.

FIG. 8 illustrates the effect of engineering the mesh properties asdescribed above on the gradient in resistance along a wedge, versus theuse of a standard ITO coating for the same shape of region. The overalldesign also includes larger conductive features in the form ofconductive leads along the left and right sides of the pattern, theleads being approximately 1 mm wide and patterned from thin film goldwith approximately 100 nanometers thickness.

Example 3

A transparent sensor element 400 for a touch screen sensor isillustrated in FIG. 9. The sensor element 400 includes two patternedconductor layers 410, 414, (e.g., an X axis layer and a Y axis layer)two optically clear adhesive layers 412, 416, and a base plate 418,laminated together and depicted as separated in FIG. 9 for clarity.Layers 410 and 414 include transparent conductive mesh bars where onelayer is oriented in the x axis direction and the other layer isorientated in the y axis direction, with reference to FIG. 2. The baseplate 418 is a sheet of glass measuring 6 centimeter by 6 centimeters inarea and 1 mm in thickness. A suitable optically clear adhesive isOptically Clear Laminating Adhesive 8141 from 3M Company, St. Paul,Minn. For each of the X-layer and the Y-layer, a clear polymer film witha micropattern of metal is used. A micropattern of thin film goldaccording to the following description is deposited onto a thin sheet ofPET. Suitable PET substrates include ST504 PET from DuPont, Wilmington,Del., measuring approximately 125 micrometers in thickness.

The micropattern 440 is depicted in FIG. 10 and FIG. 11. The thicknessof the gold is about 100 nanometers. The micropattern has transparentconductive regions in the form of a series of parallel mesh bars 442. Inaddition to mesh bars that are terminated with square pads 460(approximately 2 mm by 2 mm in area, comprising continuous conductor inthe form of thin film gold with thickness approximately 100 nanometers)for connection to an electronic device for capacitive detection offinger touch to the base plate, there are mesh bars 441 that areelectrically isolated from the electronic device. The isolated mesh bars441 serve to maintain optical uniformity across the sensor. Each bar iscomprised of a mesh made up of narrow metallic traces 443, the traces443 measuring approximately 5 micrometers in width. The mesh bars eachmeasure approximately 2 mm in width and 66 mm in length. Within eachmesh bar are rectangular cells measuring approximately 0.667 mm in widthand 12 mm in length. This mesh design serves to provide ties betweenlong-axis traces in each mesh bar, to maintain electrical continuityalong the mesh bar, in case of any open-circuit defects in the long axistraces. However, as opposed to the use of a square mesh with 0.667 mmpitch having such ties, the rectangular mesh of FIG. 10 and FIG. 11trades off sheet resistance along the mesh bar with opticaltransmittance more optimally. More specifically, the mesh bar depictedin FIG. 10 and FIG. 11 and a 2 mm wide mesh bar comprising a square meshwith 0.667 mm pitch would both have essentially the same sheetresistance along the long axis of the mesh bar (approximately 50 ohmsper square); however, the square grid would occlude 1.5% of the area ofthe transparent conductive region and the mesh depicted in FIG. 10 andFIG. 11 occludes only 0.8% of the area of the transparent conductiveregion.

Example 4

A transparent sensor element for a touch screen sensor is described. Thesensor element includes two patterned conductor layers, two opticallyclear adhesive layers, and a base plate as depicted in FIG. 9. The baseplate is a sheet of glass measuring 6 centimeter by 6 centimeters inarea and 1 mm in thickness, laminated together as depicted in FIG. 9. Asuitable optically clear adhesive is Optically Clear Laminating Adhesive8141 from 3M Company. For each of the X-layer and the Y-layer, a clearpolymer film with a micropattern of metal is used. A micropattern ofthin film gold according to the following description is deposited ontoa thin sheet of PET. Suitable PET substrates include ST504 PET fromDuPont, measuring approximately 125 micrometers in thickness.

The micropattern 540 is depicted in FIG. 12 and FIG. 13. The thicknessof the gold is 100 nanometers. The micropattern 540 has transparentconductive regions in the form of a series of parallel mesh bars 542. Inaddition to mesh bars 542 that are terminated with square pads 560 forconnection to an electronic device for capacitive detection of fingertouch to the base plate, there are straight line segments 541 that areelectrically isolated from the electronic device. The straight linesegments 541 lie in regions between the mesh bars 542, with essentiallythe same geometry as the mesh bars, except for approximately 25micrometer breaks 550 as depicted in FIG. 13. The isolated line segments541 serve to maintain optical uniformity across the sensor. Each bar 542is comprised of a mesh made up of narrow metallic traces, the tracesmeasuring approximately 5 micrometers in width. The mesh bars 542 eachmeasure approximately 2 mm in width and 66 mm in length. Within eachmesh bar 542 are rectangular cells measuring approximately 0.667 mm inwidth and 12 mm in length. The mesh 542 depicted in FIG. 12 and FIG. 13occludes 0.8% of its area within the transparent conductive region. Theisolated line segments 541 depicted in FIG. 12 and FIG. 13 also occlude0.8% of the area within the region they occupy between the mesh bars542.

Example 5

A transparent sensor element for a touch screen sensor is described. Thesensor element includes two patterned conductor layers, two opticallyclear adhesive layers, and a base plate as depicted in FIG. 9. The baseplate is a sheet of glass measuring 6 centimeter by 6 centimeters inarea and 1 mm in thickness, laminated together as depicted in FIG. 9. Asuitable optically clear adhesive is Optically Clear Laminating Adhesive8141 from 3M Company. For each of the X-layer and the Y-layer, a clearpolymer film with a micropattern of metal is used. A micropattern ofthin film gold according to the following description is deposited ontoa thin sheet of PET. Suitable PET substrates include ST504 PET fromDuPont, measuring approximately 125 micrometers in thickness.

The micropattern 640 is depicted in FIG. 14 and FIG. 15. The thicknessof the gold is about 100 nanometers. The micropattern 640 hastransparent conductive regions in the form of a series of parallel meshbars 642. In addition to mesh bars 642 that are terminated with squarepads 660 for connection to an electronic device for capacitive detectionof finger touch to the base plate, there are straight line segments 641that are electrically isolated from the electronic device. The straightline segments 641 lie in regions between the mesh bars, with a similargeometry to the line segments of the mesh bars. The electricallyisolated line segments 641 serve to maintain optical uniformity acrossthe sensor. Each bar 641, 642 is comprised of narrow metallic traces,the traces measuring approximately 3 micrometers in width. The mesh bars642 each measure approximately 2 mm in width and 66 mm in length. Withineach mesh bar 642 comprising randomly shaped cells. The mesh 642depicted in FIG. 14 and FIG. 15 occludes less than 5 percent of its areawithin the transparent conductive region. The isolated line segments 641depicted in FIG. 14 and FIG. 15 also occlude less than 5 percent of thearea within the region they occupy between the mesh bars.

Example 6

A transparent sensor element was fabricated and combined with a touchsensor drive device as generally shown in FIGS. 16, 17 and 18 usingmicrocontact printing and etching as described in co-assignedapplication having an attorney docket number 64062US004. The device wasthen integrated with a computer processing unit connected to a displayto test the device. The device was able to detect the positions ofmultiple single and or simultaneous finger touches, which was evidencedgraphically on the display.

Formation of a Transparent Sensor Element

First Patterned Substrate

A first visible light substrate made of polyethylene terephthalate (PET)having a thickness of 125 micrometers (μm) was vapor coated with 100 nmsilver thin film using a thermal evaporative coater to yield a firstsilver metalized film. The PET was commercially available as productnumber ST504 from E.I. du Pont de Nemours, Wilmington, Del. The silverwas commercially available from Cerac Inc., Milwaukee, Wis. as 99.99%pure 3 mm shot.

A first poly(dimethylsiloxane) stamp, referred to as PDMS andcommercially available as product number Sylgard 184, Dow Chemical Co.,Midland, Mich., having a thickness of 3 mm, was molded against a 10 cmdiameter silicon wafer (sometimes referred to in the industry as a“master”) that had previously been patterned using standardphotolithography techniques. The PDMS was cured on the silicon wafer at65° C. for 2 hours. Thereafter, the PDMS was peeled away from the waferto yield a first stamp having two different low-density regions withpatterns of raised features, a first continuous hexagonal mesh patternand a second discontinuous hexagonal mesh pattern. That is, the raisedfeatures define the edges of edge-sharing hexagons. A discontinuoushexagon is one that contains selective breaks in a line segment. Theselective breaks had a length less than 10 μm. The breaks were designedand estimated to be approximately 5 μm. In order to reduce theirvisibility, it was found that preferably, the breaks should be less than10 μm, more preferably 5 μm or less, e.g., between 1 and 5 μm. Eachraised hexagon outline pattern had a height of 2 μm, had 1% to 3% areacoverage, corresponding to 97% to 99% open area, and line segments thatmeasured from 2 to 3 μm in width. The first stamp also included raisedfeatures defining 500 μm wide traces. The first stamp has a firststructured side that has the hexagonal mesh pattern regions and thetraces and an opposing second substantially flat side.

The stamp was placed, structured side up, in a glass Petri dishcontaining 2 mm diameter glass beads. Thus, the second, substantiallyflat side was in direct contact with the glass beads. The beads servedto lift the stamp away from the base of the dish, allowing the followingink solution to contact essentially all of the flat side of the stamp. A10 millimolar ink solution of 1-octadecanethiol (product number C18H3CS,97%, commercially available from TCI America, Portland Oreg.) in ethanolwas pipetted into the Petri dish beneath the stamp. The ink solution wasin direct contact with the second substantially flat side of the stamp.After sufficient inking time (e.g., 3 hours) where the ink has diffusedinto the stamp, the first stamp was removed from the petri dish. Theinked stamp was placed, structured side up, onto a working surface. Thefirst silver metalized film was applied using a hand-held roller ontothe now inked structured surface of the stamp such that the silver filmwas in direct contact with the structured surface. The metalized filmremained on the inked stamp for 15 seconds. Then the first metalizedfilm was removed from the inked stamp. The removed film was placed forthree minutes into a silver etchant solution, which contained (i) 0.030molar thiourea (product number T8656, Sigma-Aldrich, St. Louis, Mo.) and(ii) 0.020 molar ferric nitrate (product number 216828, Sigma-Aldrich)in deionized water. After the etching step, the resulting firstsubstrate was rinsed with deionized water and dried with nitrogen gas toyield a first patterned surface. Where the inked stamp made contact withthe silver of the first metalized substrate, the silver remained afteretching. Thus silver was removed from the locations where contact wasnot made between the inked stamp and silver film.

FIGS. 16, 16 a and 16 b show a first patterned substrate 700 having aplurality of first continuous regions 702 alternating between aplurality of first discontinuous regions 704 on a first side of thesubstrate, which is the side that contained the now etched and patternedsilver metalized film. The substrate has an opposing second side that issubstantially bare PET film. Each of the first regions 702 has acorresponding 500 μm wide conductive trace 706 disposed at one end. FIG.16a shows an exploded view of the first region 702 having a plurality ofcontinuous lines forming a hexagonal mesh structure. FIG. 16b shows anexploded view of the first discontinuous region 704 having a pluralityof discontinuous lines (shown as selective breaks in each hexagon)forming a discontinuous hexagonal mesh structure. The breaks weredesigned and estimated to be approximately 5 μm. In order to reducetheir visibility, it was found that preferably, the breaks should beless than 10 μm, more preferably 5 μm or less, e.g., between 1 and 5 μm.Each mesh structure of regions 702 and 704 had 97% to 99% open area.Each line segment measured from 2 to 3 μm.

Second Patterned Substrate

The second patterned substrate was made as the first patterned substrateusing a second visible light substrate to produce a second silvermetalized film. A second stamp was produced having a second continuoushexagonal mesh pattern interposed between a second discontinuoushexagonal mesh pattern.

FIGS. 17, 17 a and 17 b show a second patterned substrate 720 having aplurality of second continuous regions 722 alternating between aplurality of second discontinuous regions 724 on a first side of thesecond substrate. Each of the second regions 722 has a corresponding 500μm wide second conductive trace 726 disposed at one end. FIG. 17a showsan exploded view of one second region 722 having a plurality ofcontinuous lines forming a hexagonal mesh structure. FIG. 17b shows anexploded view of one second discontinuous region 724 having a pluralityof discontinuous lines (shown as selective breaks in each hexagon)forming discontinuous hexagonal mesh structure. Each mesh structure ofregion 722 and 724 had 97% to 99% open area. Each line segment measuredfrom 2 to 3p.m.

Formation of a Projected Capacitive Touch Screen Sensor Element

The first and second patterned substrates made above were used toproduce a two-layer projected capacitive touch screen transparent sensorelement as follows.

The first and second patterned substrates were adhered together usingOptically Clear Laminating Adhesive 8141 from 3M Company, St. Paul,Minn. to yield a multilayer construction. A handheld roller was used tolaminate the two patterned substrates with the regions of the first andsecond conductive trace regions 706 and 726 being adhesive free. Themultilayer construction was laminated to a 0.7 mm thick float glassusing Optically Clear Laminating Adhesive 8141 such that the first sideof the first substrate was proximate to the float glass. The adhesivefree first and second conductive trace regions 706 and 726 allowedelectrical connection to be made to the first and second patternedsubstrates 700 and 720.

FIG. 18 shows a top plan view of a multilayer touch screen sensorelement 740 where the first and second patterned substrate have beenlaminated. Region 730 represented the overlap of the first and secondcontinuous regions. Region 732 represented the overlap of the firstcontinuous region and the second discontinuous region. Region 734represented the overlap of the second continuous region and the firstdiscontinuous region. And, region 736 represented the overlap betweenthe first and second discontinuous regions. While there was a pluralityof these overlap regions, for ease of illustration, only one region ofeach has been depicted in the figure.

The integrated circuits used to make mutual capacitance measurements ofthe transparent sensor element were PIC18F87J10 (Microchip Technology,Chandler, Ariz.), AD7142 (Analog Devices, Norwood, Mass.), andMM74HC154WM (Fairchild Semiconductor, South Portland, Me.). ThePIC18F87J10 was the microcontroller for the system. It controlled theselection of sensor bars which MM74HC154WM drives. It also configuredthe AD7142 to make the appropriate measurements. Use of the systemincluded setting a number of calibration values, as is known in the art.These calibration values can vary from touch screen to touch screen. Thesystem could drive 16 different bars and the AD7142 can measure 12different bars. The configuration of the AD7142 included selection ofthe number of channels to convert, how accurately or quickly to takemeasurements, if an offset in capacitance should be applied, and theconnections for the analog to digital converter. The measurement fromthe AD7142 was a 16 bit value representing the capacitance of the crosspoint between conductive bars in the matrix of the transparent sensorelement.

After the AD7142 completed its measurements it signaled themicrocontroller, via an interrupt, to tell it to collect the data. Themicrocontroller then collected the data over the SPI port. After thedata was received, the microcontroller incremented the MM74HC154WM tothe next drive line and cleared the interrupt in the AD7142 signaling itto take the next set of data. While the sampling from above wasconstantly running, the microcontroller was also sending the data to acomputer with monitor via a serial interface. This serial interfaceallowed a simple computer program, as are known to those of skill in theart, to render the raw data from the AD7142 and see how the values werechanging between a touch and no touch. The computer program rendereddifferent color across the display, depending on the value of the 16 bitvalue. When the 16 bit value was below a certain value, based on thecalibration, the display region was rendered white. Above thatthreshold, based on the calibration, the display region was renderedgreen. The data were sent asynchronously in the format of a 4 byteheader (0xAAAAAAAA), one byte channel (0x00-0x0F), 24 bytes of data(represents the capacitive measurements), and carriage return (0x0D).

Results of Testing of the System

The transparent sensor element was connected to the touch sensor drivedevice. When a finger touch was made to the glass surface, the computermonitor rendered the position of touch that was occurring within thetouch sensing region in the form of a color change (white to green) inthe corresponding location of the monitor. When two finger touches weremade simultaneously to the glass surface, the computer monitor renderedthe positions of touches that were occurring within the touch sensingregion in the form of a color change (white to green) in thecorresponding locations of the monitor. When three finger touches weremade simultaneously to the glass surface, the computer monitor renderedthe positions of touches that were occurring within the touch sensingregion in the form of a color change (white to green) in thecorresponding locations of the monitor.

Thus, embodiments of the TOUCH SCREEN SENSOR HAVING VARYING SHEETRESISTANCE are disclosed. One skilled in the art will appreciate thatthe present invention can be practiced with embodiments other than thosedisclosed. The disclosed embodiments are presented for purposes ofillustration and not limitation, and the present invention is limitedonly by the claims that follow.

What is claimed is:
 1. A patterned substrate comprising electricallyconductive first and second meshes having respective different first andsecond sheet resistances and defining a plurality of enclosed respectivefirst and second open areas, at least one of the first and second mesheshaving an open area of greater than about 50 percent, the second meshelectrically connected to the first mesh and to an electricallyconductive pad for connection to an electronic device, the first mesh,the second mesh and the pad comprising a same metal at approximately asame thickness.
 2. The patterned substrate of claim 1 further comprisinga plurality of selective breaks in an otherwise continuous mesh.
 3. Thepatterned substrate of claim 1, wherein a at least one of the first andsecond meshes has an open area of greater than about 75 percent.
 4. Thepatterned substrate of claim 1, wherein a at least one of the first andsecond meshes has an open area of greater than about 80 percent.
 5. Thepatterned substrate of claim 1, wherein a at least one of the first andsecond meshes has an open area of greater than about 90 percent.
 6. Thepatterned substrate of claim 1, wherein at least one of the first andsecond mesh comprises electrically conductive traces having widthsbetween 0.5 and 25 micrometers.
 7. The patterned substrate of claim 1,wherein the metal comprises one or more of gold, silver, palladium,platinum, aluminum, copper, nickel, and tin.